Allergy is a faulty response of the immune system against different daily factors which usually do not cause any response. The mechanisms which the immune system uses in order to protect our body from foreign intruders are alike the mechanisms which are being used by hypersensitivity response to harm our body. Meaning, antibodies and additional immune cells which are normal protective ingredients of the immune system, are involved with allergic reactions.
The allergic reactions can be minor (watery eyes, sneezing) and also severe (life threatening). The best treatment today is avoiding contact with the allergen, a customary medicinal treatment is using medications which contradict histamines that delay the activity of the cells which are responsible for the allergic reaction.